The 18k ring has hallmarks that I do not recognize. Testing with nitric acid and a "kee" tester it is 18k solid yellow gold. The ring weighs 8.6 grams. Set in the center is a oval 7.3 x 5.8 blue natural persian turquoise . Set around the center stone are 12 rose cut natural diamonds. It wears to a size 7.5 and can be resized. The gold may need a light polish.